The present invention relates to a sheet of glass for use as a window glass sheet on an automobile or the like.
Window glass sheets on automobiles are bonded along their peripheral edges to window frames with strips of urethanes interposed therebetween. As shown in FIG. 3 of the accompanying drawings, one recently proposed window glass sheet 1 has a peripheral edge printed with a blackish ceramic collar 2 for preventing the bonded peripheral edge from being deteriorated by ultraviolet radiation and also for concealing an unsightly deposit of dirt and dust.
Where the glass sheet 1 is used as a rear window glass sheet, it is known that the glass sheet 1 is printed with electrically conductive wires 3 for defrosting the glass sheet 1, and also with bus bars 4 on opposite sides for supplying an electric current to the conductive wires 3. These conductive wires 3 and bus bars 4 are formed by baking a silver paste. The ceramic collar 2 is formed by baking a ceramic paste. The bus bars 4 are positioned in the ceramic collar 2. To form the bus bars 4 and the ceramic collar 2, a ceramic paste is printed on the inner surface of the glass sheet, and a silver paste is then printed on the printed ceramic paste. Thereafter, the glass sheet is heated and bent, whereupon the ceramic paste and the silver paste are baked by the heat of the glass sheet.
The ceramic paste and the silver paste are baked at a temperature in the range of from 600.degree. to 700.degree. C. at which the glass sheet is shaped. At this time, lead glass of a low melting point (frit) in the ceramic paste is dispersed in the silver paste, lowering the proportion of silver in the baked bus bars 4. If the proportion of silver in the baked bus bars 4 is reduced, then the bonding strength with which terminals are soldered to the bus bars 4 decreases.
To avoid the above shortcoming, it has been customary to have portions of the bus bars 4 project from the ceramic collar 2 and to bond terminals 5 to the projecting portions of the bus bars 4, as shown in FIG. 3. Alternatively, as illustrated in FIG. 4, each of the ceramic collars 2 has a recess 6 in which a terminal 5 bonded to the bus bar 4 is positioned.
The arrangement shown in FIG. 3 is disadvantageous in that the design of the printed pattern is not desirable since the terminals are exposed to external view, and that the conductive wires required must be long because the terminals are positioned inwardly of the bus bars 4. Problems with the structure shown in FIG. 4 are that the printing process is complex and costly because of the recess 6 defined in the ceramic collar 2. One proposal to increase the bonding strength of the terminals 5 would be to deposit a plated layer on the bus bars 4. However, no sufficient bonding strength would be achieved by such a plated layer on the bus bars 4. The above drawbacks hold true for the bonded connection between an antenna wire and its terminal on a front window glass sheet, or a windshield.